This invention relates to the use of monoclonal antibody to the H-Y antigen for diagnosing the sex of a mammalian and avian cell, i.e. that one can determine whether that cell is derived from an individuum carrying a Y chromosome or not. Therefore, this diagnostic process can determine the gender of individuum of a wide range of species, inclusive, but not limited to, mammals and birds.
In man, in fact all mammals, sex is determined by the inheritance of the Y chromosome. Obviously, this derives from the male, which produces two types of germ cells, Y-bearing and X-bearing spermatozoa. On fertilization with the X-bearing ovum, two types of zygotes (fertilized eggs) result in statistical proportions, usually near 50/50. Zygotes with XX constellation develop to females, whereas those of XY constellation become males. The laws of Genetics therefore generally dictate that all male cells (except haploid germ cells and erythrocytes) carry X and Y chromosomes and those of the female XX chromosomes. Although a reversal of this general rule is noted in some animals e.g. birds, the determination is still applicable although with reversed interpretation.
The secondary (phenotypic) sexual development of the male is under the influence of hormones, however, little is known about the primary (gonadal) sexual development. It is thought that the Y-chromosome directs the production of a product (s) which induces in early embryonal life a cascade of events that lead to the expression of the male phenotype. For instance, there is good evidence that products of the Y chromosome direct undifferentiated gonads to develop towards testis, and this is one of the first crucial events in the aforementioned cascade. It is important to note that in the absence of properly functioning Y products the gonads of mammals follow a preset pathway leading to formation of ovaries. Today the exciting possibility exists that the inducer of testicular differentiation has been identified as the H-Y antigen. This assumption is hypothetical, but it should be mentioned that the following application of this biological principle is not essentially dependent upon the role of H-Y in sex differentiation. It is important to note that most male cells of the mammals, starting with early embryonal age, express the H-Y antigen.